Method and apparatus for sorting and separating granular mixture

ABSTRACT

A minority of grains, having a low suspension velocity, and a majority of grains, having a higher suspension velocity, are sorted and separated from mixtures of granular material under the influence of swinging-throw movements, of a plane inclined gaspermeable material support, on material charged at an inlet, and of an air current flowing upwardly through the support and placing the material conducted thereover in a state of suspension. The swinging-throw movement is used to conduct the majority grains from the inlet over a horizontal path to effect discharge thereof, and the minority grains, floating in a state of suspension, are discharged in a range defined by a material fall line, extending downwardly from the inlet, and a line having an inclination, relative to the inlet, which is half the fall line inclination relative to the inlet. The apparatus includes a gas-permeable support which is planar and comprises a fine mesh screen disposed above a perforated &#39;&#39;&#39;&#39;scale&#39;&#39;&#39;&#39; plate, and the support is compartmented. The support has an articulated mounting on rocker members which can be adjusted, in a universal manner, as to angle of inclination, with the material support being vibrated by an electric motor provided with ecccentric weights.

Feb. 4, 1975 METHOD AND APPARATUS FOR SORTING AND SEPARATING GRANULAR MIXTURE [76] Inventor: Hans Oetiker, Salisstr. 4,CH-9000 St. Gallen, Switzerland [22] Filed: Dec. 27, 1973 [21] Appl. No.: 428,890

Related U.S. Application Data [63] Continuation of Ser. No, 167,933, Aug, 2, 1971,

abandoned.

[30] Foreign Application Priority Data Aug, 3, 1970 Switzerland 11641/70 [52] U.S. Cl 209/469, 209/467, 209/498, 209/504 [51] Int. Cl 1307b 4/08 [58] Field of Search 209/466-469, 209/504, 485, 498, 486

[56] References Cited UNITED STATES PATENTS 775,947 11/1904 Stebbins H 209/474 1,315,881 9/1919 Sutton et a1 209/467 1,579,993 4/1926 Andre 209/469 2,038,126 4/1936 Peale, Jr. 209/492 X 2,139,823 12/1938 Haworth 209/467 2,242,562 5/1941 Weber 209/498 X 2,309,355 1/1943 Peale et al. 209/467 2,353,543 7/1944 Brusset 209/469 2,361,601 10/1944 Carter 209/467 2,404,414 7/1946 Sutton 209/467 2,596,015 5/1952 Dunwody 209/467 X Primary ExaminerFrank W. Lutter Assistant Examiner-Ralph J. Hill Attorney, Agent, or Firm-McGlew and Tuttle [57] ABSTRACT A minority of grains, having a low suspension velocity, and a majority of grains, having a higher suspension velocity, are sorted and separated from mixtures of granular material under the influence of swingingthrow movements, of a plane inclined gas-permeable material support, on material charged at an inlet, and of an air current flowing upwardly through the support and placing the material conducted thereover in a state of suspension. The swinging-throw movement is used to conduct the majority grains from the inlet over a horizontal path to effect discharge thereof, and the minority grains, floating in a state of suspension, are discharged in a range defined by a material fall line, extending downwardly from the inlet, and a line having an inclination, relative to the inlet, which is half the fall line inclination relative to the inlet. The apparatus includes a gas-permeable support which is planar and comprises a fine mesh screen disposed above a perforated scale" plate, and the support is compartmented, The support has an articulated mounting on rocker members which can be adjusted, in a universal manner, as to angle of inclination, with the material support being vibrated by an electric motor provided with ecccentric weights.

3 Claims, 6 Drawing Figures I'QKTEHTEU FEB 41975 SHEET 10F 4 METHOD AND APPARATUS FOR SORTING AND SEPARATING GRANULAR MIXTURE CROSS REFERENCE TO RELATED APPLICATION This application is a continuation of application Ser. No. 167,933, filed Aug. 2, l97l, and now abandoned.

FIELD OF THE INVENTION This invention relates to the sorting and separating of mixtures of granular material and, more particularly, to a novel method of and apparatus for sorting and separating a minority of grains, having a low suspension velocity, and a majority ofgrains, having a higher suspension velocity, for mixtures of granular material.

BACKGROUND OF THE INVENTION By the term suspension velocity as used hereinafter, is to be understood that velocity of rising air current which can maintain a granular material contained therein in suspension. In this state of suspension, the position of the granular material thus does not change either upwardly or downwardly. For this term suspension velocity there is also being used at present, in German speaking countries, a term which may be translated as end falling velocity.

In methods and apparatus of the above-mentioned type, it is known, from German Pat. No. 1,083,105 and US. Pat. No. 2,718,307, to convey those grains having a high suspension velocity from the inlet along a rising path to the corresponding outlet. The grains having a lower suspension velocity are conveyed along a substantially horizontal path to the respective outlet. It is also known, from Canadian Pat. No. 447,173, to convey both the grains having a high suspension velocity and the grains having a low suspension velocity through the inlet of the mixture to the corresponding outlets. The outlet for the heavy fractions is arranged at the upper end ofan inclined material support, and the outlet for the light fractions is arranged at the lower end of the material support.

SUMMARY OF THE INVENTION The objective of the present invention is to improve a method of the above-mentioned type in order to obtain a better suspension between the grains having respective high and low suspension velocities, and to attain a higher output (kg/mixture/unit of time), as well as to provide an apparatus for performing the method.

In accordance with the invention, this objective is attained in that the majority grains are conveyed, by the swinging-throw movements, along a horizontal path and discharged, and that the minority grains, floating down in a state of suspension, are discharged and arranged between the fall line and a line having an inclination, relative to the inlet, which is half the fall line inclination relative to the inlet. For performing the method, the present invention provides, for the discharge of the majority grains, to orient the direction of conveyance away from the range of the inlet and along a horizontal path on the material support, with the outlet for the majority grains being in this zone. The invention further provides, for the floating evacuation of the minority grains on the material support, a flow range below the above-mentioned horizontal path and through the range of the inlet between the fall line and the line having half the inclination of the fall line. The

outlet for the minority grains is arranged in this flow region, and the direction of the swinging-throw movements, produced by a swing drive, is oriented in an acute angle to and in the direction of conveyance.

An object of the invention is to provide an improved method for sorting and separating a minority of grains, having a low suspension velocity, and a majority of grains, having a higher suspension velocity, for mixtures of granular material.

Another object of the invention is to provide an improved apparatus for performing such a method.

A further object of the invention is to provide such a method and apparatus capable of obtaining a better separation between those grains having a high suspension velocity and those grains having a low suspension velocity.

Another object of the invention is to provide such a method and apparatus providing a higher output per unit of time.

For an understanding of the principles of the invention, reference is made to the following description of typical embodiments thereof as illustrated in the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS In the drawings:

FIG. I is a schematic representation of a first embodiment of the invention method;

FIG. 2 is a schematic representation of a second embodiment of the invention method;

FIG. 3 is an elevation view of apparatus for performing the invention method, looking in the direction of the arrow III of FIG. 4;

FIG. 4 is an elevation view of the apparatus looking in the direction of the arrow IV of FIG. 3;

FIG. 5 is a sectional view taken along the line VV of FIG. 3; and

FIG. 6 is a sectional view taken along the line VIV| of FIG. 5, with parts being omitted.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to FIG. 1, the plane of a swingable inclined material support, traversed by air, is indicated by the line S and the pitch angle a. The material enters the material support in the range of an inlet E. The outlet for the grains having a high suspension velocity is indi cated at A' and the outlet for the grains having a low suspension velocity is indicated at A The double arrow W indicates the direction of the swinging-throw movement of the material support. Reference character F indicates the fall line through inlet E, and reference character H indicates a horizontal line extending through inlet E. The broken line B indicates the course of a boundary for the material support.

A mixture entering the material support at inlet E is sorted into layers under the influence of the air current, with the grains having a high suspension velocity, and which rests on the material support as the bottom layer, being conveyed in the direction of the arrow PI along the horizontal line H toward outlet A' due to the swinging-throw movement, indicated by the double arrow W, and the arrangement of the terminal wall B The grains having a low suspension velocity, sorted out above the bottom layer, follow, guided partly by a terminal wall 8,, and flow along the fall line F, as indicated by the arrow P,, to outlet A in the embodiment of the method schematically illustrated in H6. 2, parts identical with those in FIG. 1 have been indicated by the same reference character. This embodiment differs from the embodiments sche matically illustrated in FIG. 1 in that outlet A for those grains having a low suspension velocity. is not arranged on the fall line F extending through inlet E' but is displaced laterally toward a line D, having an inclination which is substantially one-half the inclination of the fall line F The grains, floating away from inlet E, exclusively under the action of gravity thus follow, initially, the fall line F and then the boundary B as indicated by the arrow P This embodiment also differs from that schematically illustrated in HO. 1 by the provision of a zone Z, adjoining inlet E and arranged between the latter and outlet A and in which the mixture is subjected to a highly pulsating air current. This high pulsation necessitates a rapid layering and thus sorting of the grains. The fall line F, through outlet A intersects the horizontal line H in this zone Z',, since the grains having a low suspension velocity float away from zone Z',, under the action of gravity, along the fall line F toward outlet A in both embodiments of the method schematically illustrated in FIGS. 1 and 2, the grains having a low suspension velocity undergoe a lateral deviation toward the broken line D or D',, respectively, having an inclination angle 01/2 which is half the inclination of the fall line, due to the swinging-throw movements exerted on the underlying layers.

The apparatus for performing the method is illustrated in FIGS. 3-6 as having a housing 1 comprising a hood-shaped upper part 2 and a funnel-shaped lower part 3. On three sides, housing I defines an air permeable material support 4 comprising a screen 5, formed of wire mesh, and a perforated orifice or scale plate 6 spaced below screen in parallel relation thereto. The upper part 2 of housing 1 has a socket or nipple 7 which is connected by means of a flexible bellows 8 to a suction pipe 9 in turn connected to the intake of an air blower 10.

The lower part 3 of housing 1 is divided, by partitions it, 12 and 13 in the material support, into chambers 14-18 which form corresponding ventilation zones in material support 4, as particularly clear in H6. 5. Associated with each chamber 14,15,16 and 17 is a respective one of four axially symmetrical air inlet ports 19, while chamber 18 is connected directly to the inlet air through an opening 20 in the wall of lower housing part 3. At the inlet side of air inlet ports 19 there is mounted a disk 22 rotating about an axle 21 secured on housing 1, and provided with live axially symmetrical passages 23.

Housing 1, with material support 4, is mounted for swinging in a direction parallel to the longer side 25 of material support 4. For this purpose, two tongues 26 and 27 are connected to housing 1, and are rigidly interconnected with a tube 28. Between tongues 26 and 27 there are arranged bearing bodies 29 and 30 supporting tube 28. Bearing bodies 29 and 30 are braced, by means of coil springs 31, against respective supports 32 and 33 which are mounted on a rocker 34 and rigidly connected with the latter. On the end of housing 1 opposite tongues 26 and 27 there is secured a block 35 tapering toward its lower end, and braced by springs 36 on a support 37 which, in turn, is secured on rocker 34.

Rocker 34 is pivoted on an axle 38 extending parallel to tube 28 and which, in turn, is arranged on a second rocker 39. Second rocker 39 is pivoted on a horizontal stationary axle 40 extending toward tube 28, and fixedly mounted in two carriers 41 which are secured on a stationary base 42. Second rocker 39 has a threaded bore into which there is threaded a bolt 43 provided with a handwheel 44, and having its leading end engaging a washer 45, so that the inclination of second rocker 35 can be changed by turning handwheel 44. First rocker 34 forms, with second rocker 39, a universal joint. in the range of support 37 there is arranged, between first rocker 34 and a base 42, a scissors jack 46 whose upper arms 47 and 48 are pivoted on a pivot 49 on rocker 34, while the lower arms 50 and 51 of the jack are pivoted on a pivot 51 rigidly con nected with base 42. A bolt 54, formed with oppositely directed threads and a handwheel 53, connects the other two pivots of scissors jack 46 so that, by turning handwheel 53, rocker 34 can be pivoted about its pivot or axle 38 to change its inclination. By turning handwheels 44 and 53, it thus is possible to change both the longitudinal and the transverse inclinations of rocker 34, and thus of material support 4.

Pipe 28 also has secured thereon a holding block 55 on which a motor 56 is mounted, by means of tongues 57, for swinging in a lateral direction. On the shaft of motor 56 there are mounted, symmetrically, two eccentric weights 58, and the axis of rotation of these weights is inclined at an acute angle toward material support 4. The motor shaft, as thus arranged, produces, with the motor running, a swinging movement of material support 4 parallel to its longer side 25 and, because of the angle position to the plane of material support 4, throw movements having a predetermined stroke. Pipe 28 also has secured thereto a ratchet clutch 59 whose drive shaft is driven by motor 56 by means of a rod 60 articulated thereon, and whose free end is articulated to a tongue 61 which, in turn, is rigidly connected with motor 56. The driven shaft of clutch 59 has fixed thereto a V-belt pulley 62 driving, by means of a V-belt 63, a V-belt pulley 64 which is fixed with disk 22, so that disk 22 is thus rotated by the lateral swinging movements of the swing drive.

Along side 25 of material support 4 there are arranged three outlets 65, 66 and 67. Outlet serves to discharge grains having a high suspension velocity, and which are from -99 percent by weight of the mixture, to constitute a majority. Outlet 67 serves to discharge grains having a low suspension velocity, and which are a percentage of l-l5 percent by weight of the mixture, to constitute a minority. Mixed fractions of the minority and majority grains are discharged through outlet 66. A stowing overflow edge 68 extends along outlet 66, and grains separated from the light fractions are conveyed along this stowing overflow edge to outlet 65 under the action of the swingingthrow movement of material support 4, while the mixed fraction above the grains separated from the light fraction drops over overflow edge 68 into outlet 66. The outlets are funnel-shaped and form closed units, similar to the upper and lower housing parts 2 and 3, respectively. Adjustable flaps 97 and 98 permit variation of the inlet regions into the collecting funnels leading to the outlets. The grains falling into the outlets are discharged through respective elastic outlet funnels 99', 99" and 99", which prevent entrance of infiltrated air,

since they close automatically under the pressure gradient and open only under the weight of the separated grains ofthe majority, of the minority, and ofthe mixed fraction, to be discharged.

Opposite outlets 65, 66 and 67 there is secured, in housing 1 above material support 4, a feed trough 69. A sluicing feeding device 70, leading from a fixable tube, extends through upper housing part 2 and discharges over the rear end of feed trough 69. The granular material flows through feeding device 70 and along feed trough 69 to inlet 71 on material support 4. As best seen in FIG. 6, feed trough 69 can have several closable outlet ports 72, 73 and 74, each consisting of a respective plate 75, 76 or 77 which is rigidly connected with a respective axle 78, 79 or 80 rotatably mounted in the housing wall. These plates can be arranged coplanar or can be turned upwardly by turning the associated axles 78, 79, 80 and, depending on the position of plate 75, 76 and 77, the position of inlet 71 can be shifted along material support 4 either upwardly or downwardly.

The operation of the illustrated apparatus will now be described. By starting motor 56, material support 4 is set into vibration, performing swinging-throw movements parallel to its longer side 25. Blower I is also started, and draws in air through air inlet ports 19, material support 4 in suction pipe 9. The air flowing through air inlet ports 19 into chambers 14-17 is varied periodically by disk 22 driven by the swing drive, so that a pulsating air current flows through material support 4. Since chamber 15 presents, to screen surface adjoining inlet region 18, a substantially smaller area than do chambers 16 and 17, a much stronger pulsating air current is produced in chamber than in the range of chambers l4, l6 and 17. The part of material support 4 associated with chamber 18 produces, in this inlet region, through air opening 20, a likewise stronger but continuous air current.

The granular mixture is supplied through pipe 70, arrives over feed trough 69 in the range of inlet 71 on ma terial support 4, and is placed, by the constant air current, into a state of suspension. The grains having a low suspension velocity are layered sortingly over the sorted-out grains with a high suspension velocity sinking onto material support 4.

In this state, the gradually sorted mixture tends to flow off along the inclination in the direction of the fall line, but this tendency is counteracted by the swingingthrow movements of material support 4 directed toward wall section 82 and upper terminal wall 81, shown in FIG. 5. Wall section 82, dropping preferably slightly toward the horizontal from the range ofinlet 71 to outlet 65 for the majority grains, prevents the entering mixture from throwing off too fast into the range of chamber 15. For further separating the minority grains from the majority grains,the mixture is subjected, in chamber 15, to a highly pulsating air current. The minority grains, rising to the surface, now float in the di rection of the fall line and on the mixture to outlet 67, while the majority grains, which constitute the grains dropped onto the material support, are conveyed along a substantially horizontal line to outlet 65. This is effected substantially in a range along terminal wall 81.

Of the part of the mixture arriving at overflow edge 68, the bottom layers are retained by this edge and conducted, under the influence of the swinging-throw movements of material support 4, toward outlet 65.

The layer above the bottom layers, which is a mixed fraction of majority grains and minority grains, flows over edge 68 into outlet 66, and can be returned, in a known manner by a conveyor element which has not been shown, into the inlet region 70, 71 to be subjected again to separation. The boundaries between majority grains, minority grains, and the mixed fraction delineated by both are determined by the flaps 97 and 98.

Depending upon the type of mixture, inlet 71 can be adjusted, by turning plate 75, 76 or 77, which is effected through the substantially vertical universal joint between the base and the two rockers arranged under the center of gravity of the swinging part ofthe apparatus. Furthermore, the inclination of material support 4 can be adjusted by turning the handwheels 44 and 53, in dependence on the required degree of separation, which results primarily in a displacement of the horizontal line and of the fall line on the material support and thus in a change of the conveyance properties and flow properties of the sorted goods, for their separa tion.

It will be appreciated that the apparatus could be operated with a supply of air under positive pressure directed upwardly through the permeable material support, instead of the suction of air through the permeable material support.

The above-described embodiment illustrates the use of a screen surface formed of wire mesh and which is in contact with the material passed over it. It has been found, surprisingly, that an extremely advantageous in fluence on the sorting and separating work of the appa ratus can be attained by evenly distributed, but specially oriented, air currents through the gas-permeable material support, if the material support, in accordance with an embodiment which has not been illustrated, and over which the material is conducted, has a perfo rated orifice or scale plate with pierced holes. The pierced holes can be oriented selectively in the direction of the swinging-throw movements or in the direction of the flow region.

Pierced perforated orifice plates have been known for some time. The apertures ofthese plates are pierced in a particular manner through the plate, and not punched, which leads, on the one hand, to a rough surface of the perforated plate and, on the other hand, to an aero-dynamically peculiar type of apertures, since these are wide at the inlet side and tapered down gradually to present, at the outlet side which is at the same time the top side of the plate, narrow oblong slits. In addition, the aperturesdo not extend at a right angle through the plate, but at a certain inclination. If these inclined apertures are traversed by an air current, this results, on the one hand, in a very good air distribution over the entire surface of the perforated plate and, on the other hand, with respect to the plate surface, in oblique flow vectors which are composed of a horizontal component and a vertical component. In addition, since the piercing of the apertures into the plate for the production of a pierced perforated orifice plate results in scale-like elevations on the top surface of this plate, such a plate feels much rougher in one direction than in the opposite direction.

lt has been found that the use ofsuch a pierced perforated plate as a part of the material support in the above-described embodiment leads to considerable advantages. Thus, the design of the pierced apertures is an advantage insofar as it offers an extremely great resistance to dropping sand grains and small impurities, due to their particular design. Furthermore, it is of advantage that boundary grains, which can get into the pierced apertures and are deposited there, can leave the aperture again immediately at the bottom, due to the downward widening of the aperture. In addition, the oriented flow of the fluidization gas from the apertures pierced in a certain direction can have a decisive influence on the loosening work of the material to be conducted over them and on the velocity of flow of the loosened material over the inclined surface in the flow region from the inlet to the outlet of the minority grains. A further influence of the pierced perforated plates is exerted by the scales in cooperation with the swinging-throw movement on the material having a high and falling velocity and which is in direct contact with the material support, that is, the majority grains. These considerations show that the scales of perforated orifice plates should be oriented perferably in the direction of the swinging-throw movement for a substantial improvement of the conveyance of the majority grains in the horizontal region of the material support, which leads, at the same time, to an orientation of the pierced apertures substantially identical with this swinging-throw movement. But if, on the other hand, an accelerated evacuation of the grain with a low sus pension velocity, which normally represents the minority grains in the mixtures of granular material in these apparatuses, is to be effected, the direction of the apertures pierced through the perforated plate should be oriented preferably at an acute angle to and in the direction of the flow region from the inlet to the outlet of the minority grains. This means that, with an inclination of the material support dropping from the inlet to the outlet for the minority grains, the pierced apertures are so oriented, in the perforated plate, that a flow is produced, for the gas current, whose direction is similar to the dropping inclination.

When using such pierced perforated orifice plates in an apparatus for sorting and separating grains from mixtures of granular material under the influence of swinging-throw movements and ofa gas current placing the material in a state of suspension, a varying conveyance, and sliding behavior of the material and of the material fractions, respectively, can be obtained by a varying degree of grinding of the surface of these perforated plates. This changes, in particular, the scale nature of the plates but, at the same time, changes in the type and distribution of the air flow can also be attained. By virtue of these measures, the apparatus can be adapted to a great extent to the various sorting and separating operations, which depend primarily on different mixtures of the material, on the one hand, and on the degree of the desired separation, on the other hand.

While specific embodiments of the invention have been shown and described in detail to illustrate the application of the principles of the invention, it will be understood that the invention may be embodied otherwise without departing from such principles.

What is claimed is:

l. in apparatus for sorting and separating a minority of grains, having a low suspension velocity, and a majority of grains, having a higher suspension velocity, from mixtures of granular material, under the influence of swinging-throw movements of a plane inclined gaspermeable support and of an air current flowing upwardly through the support, and of the type including a feeding device extending to an inlet on the plane inclined gas-permeable material support, a swingable bearing carrying the material support, a swing drive operatively associated with the material support to produce the swinging-throw movements, means producing an air current flowing upwardly through the support. and outlets, for the minority grains and the majority grains, adjoining the material support: the improvement comprising, in combination, the swinging movement of said support establishing a direction of conveyance, for the discharge of the majority grains, extending from said inlet horizontally and laterally; the outlet for the majority grains being arranged in said horizontal region; means providing a flow region on the material support, located downwardly from said horizontal region, for the floating evacuation of the minority grains on the material support extending between the material fall line on said support extending through the inlet with the steepest inclination and a line on said support having an inclination which is one-half the inclination of the fall line and intersecting the inlet; the outlet for the minority grains being arranged in said lastmentioned flow region; the direction of the swingingthrow movements produced by said swing drive being oriented at an acute angle to and in the direction of conveyance; the bearing carrying said swingable mate rial support being adjustable in height both in the direction of the swinging-throw movements and at a right angle thereto, to vary the inclination of the material support with respect to a fixed base; the bearing for said material support having three support members provided with swinging elements; said three support members being connected, on one side of said swinging elements, to the swingable part of said apparatus and, on the other side of said swinging elements, to a first rocker; a second rocker; means pivotally mounting said first rocker on said second rocker; a fixed base; means pivotally mounting said second rocker on said fixed base; the axis of said last-named pivotal mounting means extending horizontally and parallel to the direction of the swinging-throw movements, and the axis of said first mentioned pivotal mounting extending at a right angle thereto; and means operatively associated with each rocker and operable to adjust the inclination thereof.

2. Apparatus as claimed in claim 1, in which said three support elements constitute a three-point bearing around the center of gravity of the swingable part of said apparatus.

3. Apparatus as claimed in claim 1, in which said rockers and their pivotal mountings constitute a universal mounting whose intersection is substantially vertically beneath the center of gravity of the swingable part of said apparatus. 

1. In apparatus for sorting and separating a minority of grains, having a low suspension velocity, and a majority of grains, having a higher suspension velocity, from mixtures of granular material, under the influence of swinging-throw movements of a plane inclined gas-permeable support and of an air current flowing upwardly through the support, and of the type including a feeding device extending to an inlet on the plane inclined gaspermeable material support, a swingable bearing carrying the material support, a swing drive operatively associated with the material support to produce the swinging-throw movements, means producing an air current flowing upwardly through the support, and outlets, for the minority grains and the majority grains, adjoining the material support: the improvement comprising, in combination, the swinging movement of said support establishing a direction of conveyance, for the discharge of the majority grains, extending from said inlet horizontally and laterally; the outlet for the majority grains being arranged in said horizontal region; means providing a flow region on the material support, located downwardly from said horizontal region, for the floating evacuation of the minority grains on the material support extending between the material fall line on said support extending through the inlet with the steepest inclination and a line on said support having an inclination which is one-half the inclination of the fall line and intersecting the inlet; the outlet for the minority grains being arranged in said lastmentioned flow region; the direction of the swinging-throw movements produced by said swing drive being oriented at an acute angle to and in the direction of conveyance; the bearing carrying said swingable material support being adjustable in height both in the direction of the swinging-throw movements and at a right angle thereto, to vary thE inclination of the material support with respect to a fixed base; the bearing for said material support having three support members provided with swinging elements; said three support members being connected, on one side of said swinging elements, to the swingable part of said apparatus and, on the other side of said swinging elements, to a first rocker; a second rocker; means pivotally mounting said first rocker on said second rocker; a fixed base; means pivotally mounting said second rocker on said fixed base; the axis of said last-named pivotal mounting means extending horizontally and parallel to the direction of the swinging-throw movements, and the axis of said first mentioned pivotal mounting extending at a right angle thereto; and means operatively associated with each rocker and operable to adjust the inclination thereof.
 2. Apparatus as claimed in claim 1, in which said three support elements constitute a three-point bearing around the center of gravity of the swingable part of said apparatus.
 3. Apparatus as claimed in claim 1, in which said rockers and their pivotal mountings constitute a universal mounting whose intersection is substantially vertically beneath the center of gravity of the swingable part of said apparatus. 